Understanding a baby’s movements during a vaginal birth.
Updated: Jun 19, 2020
I believe that visualisation is a key factor in having an empowered birth. Knowing the essential movements of a baby during a vaginal birth can help us to feel more connected with our baby and our own body during a very physically and emotionally demanding time.
I also think that having knowledge about what goes on in birth gives us an appreciation for what a woman’s body can do, for the intricate interplay between the mother’s body and the baby’s physical reactions as well as what an incredible journey it is for the baby.
I know that when I read about the physiology of birth, I always feels a sense of immense gratitude.
What are CARDINAL MOVEMENTS?
Cardinal movements are 7 specific movements that a baby must complete to exit the mother’s pelvis effectively. It involves certain positions, rotations and movements of the baby’s head to navigate the best route possible for exiting that narrow bony passage.
See video of “cardinal movements”.
*I’m referring to the baby as a male for simple differentiation between the baby and mother.
The baby’s head enters his mother’s pelvis. This can occur before or after contractions commence.
The baby’s head drops further into the pelvis so that his head comes into contact with the bony points of his mother’s pelvis called “the ischial spines”.
As the baby descends onto his mother’s pelvic floor, it causes him to tuck his chin down onto his chest. This makes the presenting part of his head, as small as possible!
4. Internal rotation
The widest part of a mother’s pelvis is different from top to bottom thanks to the different pelvic bones and joints.
As the baby presses onto his mother’s pelvic floor, it causes him to twist his head slightly. This allows him to navigate through the pelvic floor and also to make use of the changing shape of his mother’s pelvis. If he doesn’t perform this action, it can result in a posterior or “back” labour which is more difficult, slow and painful.
In this position the baby can make use of the flexible joints of his mother’s sacrum and tailbone to essentially swing out of the way.
This is the moment when the baby’s head, face and chin is born. The baby lifts his chin and is squeezed out beneath the bones at the front of his mother’s pelvis also known as the “pubic arch”.
6. External rotation
Now the baby must turn once more to birth the shoulders. He turns to face his mother’s inner thighs and the body will follow suit. Again, this allows the baby to make use of the widest and most flexible part of his mother’s pelvis.
7. Expulsion (I’m not sure I like this word to describe this part but it is the “technical” term)
The baby releases his top shoulder from under his mother’s pubic arch and then the bottom shoulder is released from his mother’s perineum and the rest of his body is born.
What is the Chiropractor’s role in preparing a woman’s body for a vaginal birth?
Our role is to make sure there are no obstacles that could impede the baby’s ability to perform these cardinal movements effectively. As you have read above, the movements of the baby heavily rely on the interplay between him and the joints, bones and soft tissue of the mother’s pelvis.
If there are obstacles of the pelvis causing even the slightest constraint or imbalance, these movements can be very difficult for the baby to perform. This can sometimes result in the following:
Taking much longer for the baby to descend;
Leading to failure to progress (cervix taking too long to dilate);
Leading to a posterior labour (baby’s spine in on your spine) causing more pain and further prolonging;
Leading to breech or unfavourable positioning; and
Ultimately resulting in the risk of intervention including induction drugs/ pain relief/suction/forceps/episiotomies which can cause foetal distress and increase the likelihood of a caesarean section.
The care of a pregnant women in the lead up to birth includes balancing the muscles and ligaments of the pelvis, maximising joint alignment and flexibility, posture correction and strengthening work. The treatment is gentle, safe and effective all without the use of cracking or manipulation style treatments.
Image Credit: Homebirth image from Reborn Within